Analysis On-board Procedures Through the application of the ISM Code, shipping companies can minimize the number of human performance decisions which may lead to an accident. With the provision of adequate, accessible policies and procedures, a ship's crew is better equipped to make day-to-day operational decisions. The company safety management procedures for lockout of equipment required that each employee attach his own lock to the lockout device. Additionally, the unloading equipment was equipped with keyed switches, which were left in the on position when not in use. The head tunnelman was supervising the maintenance of the hydraulic slewing system; however, he had not been required to watch the available instructional video, nor was he aware of the procedure binders. Notwithstanding the company's lockout procedure, the tunnelman and the assistant tunnelman were not fully aware of the status of the power supply to the boom, nor were they in control of the lockout device used. As a result, the boom power was restored without their knowledge and without the maintenance having been completed. The second officer was familiar with the controls and operation of the unloading boom, having operated it many times in the past. However, formal procedures, such as checking the oil level, making a walk-around inspection, or communicating with the engineer on watch, were not in place to help ensure that the topping lift and slewing systems were serviceable before operation. As a result, the boom was topped up before the slewing system operation was verified, resulting in the uncontrolled movement of the boom to port. Communications Communications between the various shipboard departments is vital for the safe operation of modern complex vessels. On board the ALGOBAY it was not the practice for the deck and engine-room departments to inform each other of work being conducted on a day-to-day basis. As a result, the master was unaware that the unloading boom hydraulic slewing system was unserviceable when he requested the second officer to shift the boom in an attempt to correct the vessel's port list. Engine-Room Workload With one main engine unserviceable, the chief engineer's priority was to complete the engine repair as soon as possible. He was hampered in doing so by inexperienced relief engine-room staff who required constant supervision while working on the engine. Even though he gave permission for the relatively inexperienced head tunnelman to change the oil in the unloading boom hydraulic slewing system, he was unable to provide supervision due to the demands placed upon him by the main engine repair. As a result, he was unaware that the unloading boom slewing system had not been refilled with oil when he removed the lockout tag on the slewing system power supply. Unloading Boom Control System The design of the unloading boom controls incorporated an electrical interlock that prevented the hydraulic pump for the slewing system from starting if inadequate oil was available in the header tank. However, the interlock did not interfere with the operation of the electric motor used to top up the boom. Therefore, the second officer, who did not know that the slewing system was unserviceable, was able to top up the boom from its saddle. When the boom was raised, no slewing control was available, and it rapidly swung out of control to port (in the direction of the ship's list) until its movement was arrested by the ship's accommodation. Vessel's Stopping Ability Although the ALGOBAY had sailed on one engine without incident for several months during the previous season, vessels are designed for optimal manoeuvrability when full power is available from the main propulsion system. When the propeller was put to full astern, the starboard main engine provided about 50 per cent of the total power normally available, which reduced the vessel's ability to stop. The port main engine had to be shut down for 24 hours to repair a broken cylinder head stud and cooling-water leak, resulting in the vessel proceeding towards Nanticoke on one engine. The chief engineer, third engineer, and one mechanical assistant were the only regular engine-room staff on board and, as a result, the chief engineer had to closely supervise the engine repairs. Procedures to ensure that the deck and engine-room departments exchanged information were not being followed at the time of the occurrence. The engineering staff conducted preventative maintenance on the hydraulic slewing system of the unloading boom without the deck department having been informed. The company lockout procedures for machinery maintenance were not followed. The tunnelmen did not refill the hydraulic slewing system before finishing work for the day. The chief engineer assumed multiple responsibilities occasioned by the engine repairs and hydraulic maintenance and, assuming that the hydraulic slewing system had been re-filled with oil, removed the lockout from the slewing system power supply. There were no formal operating procedures for the cargo boom that would help ensure that the hydraulic slewing system was serviceable. The slewing system low oil level interlock was not connected to the topping lift controls to prevent the boom from being topped up without adequate oil in the hydraulic slewing system. When the boom was raised, the vessel's list caused the boom to swing, uncontrolled, to port. Air trapped in the hydraulic slewing rams compressed and fractured the cylinders. The vessel's stopping ability was reduced as a result of the port main engine being unavailable. Before the vessel could be brought to a stop, the boom knocked down five light standards on the wharf.Findings The port main engine had to be shut down for 24 hours to repair a broken cylinder head stud and cooling-water leak, resulting in the vessel proceeding towards Nanticoke on one engine. The chief engineer, third engineer, and one mechanical assistant were the only regular engine-room staff on board and, as a result, the chief engineer had to closely supervise the engine repairs. Procedures to ensure that the deck and engine-room departments exchanged information were not being followed at the time of the occurrence. The engineering staff conducted preventative maintenance on the hydraulic slewing system of the unloading boom without the deck department having been informed. The company lockout procedures for machinery maintenance were not followed. The tunnelmen did not refill the hydraulic slewing system before finishing work for the day. The chief engineer assumed multiple responsibilities occasioned by the engine repairs and hydraulic maintenance and, assuming that the hydraulic slewing system had been re-filled with oil, removed the lockout from the slewing system power supply. There were no formal operating procedures for the cargo boom that would help ensure that the hydraulic slewing system was serviceable. The slewing system low oil level interlock was not connected to the topping lift controls to prevent the boom from being topped up without adequate oil in the hydraulic slewing system. When the boom was raised, the vessel's list caused the boom to swing, uncontrolled, to port. Air trapped in the hydraulic slewing rams compressed and fractured the cylinders. The vessel's stopping ability was reduced as a result of the port main engine being unavailable. Before the vessel could be brought to a stop, the boom knocked down five light standards on the wharf. The unloading boom of the ALGOBAY swung uncontrollably to port when it was topped up without oil in its hydraulic slewing system. Contributing to the occurrence was: the over-tasking of the chief engineer, due to an unscheduled engine repair; the unfamiliarity of the relief engine-room staff with the vessel and shipboard procedures; inadequate unloading equipment operating procedures; and the design of the hydraulic system, which did not have lockouts to prevent the starting of the topping lift motor if the oil level was low in the slewing system.Causes and Contributing Factors The unloading boom of the ALGOBAY swung uncontrollably to port when it was topped up without oil in its hydraulic slewing system. Contributing to the occurrence was: the over-tasking of the chief engineer, due to an unscheduled engine repair; the unfamiliarity of the relief engine-room staff with the vessel and shipboard procedures; inadequate unloading equipment operating procedures; and the design of the hydraulic system, which did not have lockouts to prevent the starting of the topping lift motor if the oil level was low in the slewing system. Safety Action Action Taken Subsequent to the occurrence, Algoma Central Marine reviewed its operating procedures for self-unloading equipment. As a result, the company has standardized operating procedures across its fleet with the following: When the boom and self-unloading equipment are not in use, the main breaker supplying the unloading switchboard is to be left open. If crew members are working on or near equipment, then the main breaker is to be padlocked open, as per the company's lockout/tagout procedures. The main breaker is to be closed by the engineer on watch, only after receiving orders to do so by the chief engineer, master, or mate on watch. The lockout keys in the control room are not to be left in the boom/unloading system when not in use. The master key which controls all of the unloading drive motors is to be used only by the chief engineer and kept in his office. The slew/hoist key is to be kept in the engine control room and may be retrieved only by the chief engineer or officer of the watch. The chief engineer is to keep and maintain marked duplicates for both keys, for emergency use only. An interlock has been installed to prevent the boom being hoisted in the event that the slewing system is not functioning. The Boom Operational Procedures have been amended to ensure that the boom is checked for operational readiness prior to use. In addition, the company has re-emphasized to the officers and crew of the ALGOBAY the importance that open interdepartmental communication plays in the safe operation of the vessel.